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The Tenderloin’s Fishiest, and Most Delicious, Noodle Soup Returns

Luke Tsai | Photo: Clark Miller | November 28, 2017

Mong Thu Cafe’s reopening is a reason for celebration.

With its diner-style counter, cute chalkboard menu, and mint-green color scheme, the newly reopened Mong Thu Cafe has the look of one of those new-retro luncheonettes cropping up around San Francisco—the latest signpost of a rapidly gentrifying Tenderloin, perhaps.

In that sense, first-time customers might be surprised to discover that the restaurant is actually a family-run Vietnamese noodle- and-sandwich shop—a cash-only spot heading into its 25th year of business, and one of the only places in the city where you can buy what is arguably the homiest noodle soup in the entire pantheon of homey Vietnamese noodle soups.

That dish, bun mam, is chef-owner Kim Nguyen’s particular specialty—a dish that owes its famously pungent and fishy-tasting broth to the inclusion of fermented fish. It’s the kind of soup that often comes with a disclaimer when someone orders it for the first time. (The chef’s daughter, Linh Nguyen, who translated for her mother, says the stuff is too pungent even for her.)

Since February, longtime customers have had to get their bun mam fix elsewhere, after the city ruled that Mong Thu’s kitchen wasn’t up to snuff. The restaurant served only banh mi for a few months, then closed entirely in June for an extended renovation. Thankfully, the story has a happy ending: With help from a grant through the city’s SF Shines business improvement program, the Nguyens were able to redo their entire kitchen. The restaurant reopened in early September.

Like many of her peers in mom-and-pop restaurantdom, Nguyen is fully self-taught. She says she would taste a dish when she was out at some café or noodle shop and then go home and try to re-create it, tinkering with the ingredients and proportions until she came up with a version that suited her palate. In that way, the tiny restaurant evolved over the years from its earliest incarnation as just a simple sandwich shop. It now boasts a surprisingly wide-ranging selection of regional Vietnamese noodle dishes, including hard-to-find specialties such as banh uot (a kind of steamed rice roll) and the Cambodian-influenced hu tieu Nam Vang (a milder noodle soup).

The bun mam is probably Mong Thu’s rarest and most popular off ering, though—a testament to the power of well-honed home-cooking chops. To this day, Nguyen says, she hasn’t tasted any version of the dish other than the one she makes herself. Some 10 years ago, a customer gave her a general description and rattled off a list of traditional ingredients. Otherwise, Nguyen’s bun mam is purely her own creation. She never even looked up a recipe.

And yet: This is a bowl of noodles that will please even the most discerning bun mam eater. The plump shrimp, tender white-fleshed fish, and thin slices of fat-striated pork are all poached just so. The spaghetti-shaped rice noodles are slippery and eminently slurpable. The accompanying herbs are impeccably fresh. But the main reason to order Mong Thu’s bun mam—and, really, any bun mam worth its funk— is the mud-colored broth itself, which doesn’t shy away from the dish’s characteristic fi shy pungency. It also has a delicate sweetness, and a tang, and a bright arpeggio of citrusy lemongrass. It is a soup that sings. 248 Hyde St. (Near Eddy St.), 415-928-6724